U.S. patent number 4,610,399 [Application Number 06/692,116] was granted by the patent office on 1986-09-09 for mixing particulate materials.
This patent grant is currently assigned to Recycloplast AG. Invention is credited to Erich Weichenrieder.
United States Patent |
4,610,399 |
Weichenrieder |
September 9, 1986 |
Mixing particulate materials
Abstract
The invention relates to the mixing of particulate materials
with a given mixing ratio and as part of a plant and process
requiring the materials, comprising the steps of metering the
materials separately in respective metering units running at least
substantially continuously, permitting the materials to fall freely
onto a horizontal conveyor belt with a planar surface with a
distribution of the materials over the belt, and supplying the
materials in a further free fall to a further processing zone as
part of the process.
Inventors: |
Weichenrieder; Erich
(Egling-Neukolbing, DE) |
Assignee: |
Recycloplast AG
(Egling-Neukolbing, DE)
|
Family
ID: |
27191627 |
Appl.
No.: |
06/692,116 |
Filed: |
January 17, 1985 |
Foreign Application Priority Data
|
|
|
|
|
Jan 19, 1984 [DE] |
|
|
3401758 |
Jan 19, 1984 [DE] |
|
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3401774 |
Jan 19, 1984 [DE] |
|
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3401789 |
|
Current U.S.
Class: |
241/101.8;
222/312; 366/153.3; 366/160.1; 366/177.1; 366/182.1; 222/272 |
Current CPC
Class: |
B29B
7/60 (20130101); B65G 53/4633 (20130101); B29B
13/10 (20130101); B29C 31/06 (20130101); B29B
7/603 (20130101); B01F 15/0483 (20130101); B29B
17/02 (20130101); B03B 9/061 (20130101); B29B
17/0412 (20130101); B29K 2105/26 (20130101); Y02W
30/52 (20150501); B29K 2705/00 (20130101); Y02W
30/62 (20150501); B29B 2017/0272 (20130101); B01F
3/18 (20130101); B29L 2007/008 (20130101) |
Current International
Class: |
B29B
17/02 (20060101); B29C 31/04 (20060101); B29B
7/60 (20060101); B29C 31/06 (20060101); B29B
7/30 (20060101); B29B 13/10 (20060101); B29B
17/04 (20060101); B01F 15/04 (20060101); B03B
9/06 (20060101); B03B 9/00 (20060101); B65G
53/46 (20060101); B65G 53/40 (20060101); B01F
3/00 (20060101); B01F 3/18 (20060101); B02C
004/00 () |
Field of
Search: |
;222/272,290,291,312,328,345
;366/8,14,71,72,73,74,76,133,147,148,152,155,160,162,181,182,186,154,177
;241/11B |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Simone; Timothy F.
Attorney, Agent or Firm: Harness, Dickey & Pierce
Claims
I claim:
1. A method of mixing particulate materials with a given mixing
ratio, said method forming part of a process requiring said
materials, comprising the steps of:
providing particulate materials to at least two metering units,
metering said materials separately each in said respective metering
unit, said metering unit operating at least substantially
continuously,
crushing said particulate materials in said metering units,
distributing said materials by free fall onto a horizontal conveyor
belt with a planar surface with a distribution of said materials
over said belt,
matching the distribution rate of said materials with the speed of
said conveyor belt such that said given desired mixing ratio is
obtained, and
supplying said materials in a further free fall to a further
processing zone as part of said process.
2. The method as claimed in claim 1 wherein said materials are
distributed in superposed layers on said conveyor belt.
3. The method as claimed in claim 1 comprising the step of
subjecting said materials on said belt to a magnetic field for the
removal of pieces of metal therefrom.
4. An apparatus for mixing at least two particulate materials
together with a given mixing ratio as part of a process plant
requiring such materials in operation, said apparatus comprising a
level, planar conveyor belt running to a processing zone within
said plant, at least two metering units placed one after the other
in succession in the direction of conveyance of said belt, each of
said metering units including means defining a metering passage for
flow of said particulate materials therethrough, said passage
stretching from an inlet port to an outlet port, means for crushing
said particulate materials positioned in said passage in each of
said metering units, said units being adapted to meter said
particulate materials at least substantially continuously, said
outlets adapted to discharge said materials in a free fall onto
said belt with a distribution onto substantially the full width of
said belt, and means for adjusting the flow rate of said
particulate material and the speed of said running conveyor belt
such that said given mixing ratio of said particulate material is
obtained.
5. The apparatus as claimed in claim 4 wherein said crushing means
comprises a rotary ribbed roll placed in said metering passage for
rotation about an axis running through said passage transversely
thereof, said roll having ribs thereon bordering shallow
trough-like depressions therebetween, said ribs being helical with
respect to said axis and running from end to end of said roll.
6. The apparatus as claimed in claim 4 comprising one such ribbed
roll located in each said passage, a stationary knife placed for
cooperating with said ribs in defining a restricted gap as part of
said passage, leading edges of said ribs being in the form of
cutting edges for shearing said materials against said knife.
7. The apparatus as claimed in claim 6 comprising two such knives
in said passage on two sides of the ribbed roll.
8. The apparatus as claimed in claim 6 wherein each unit comprises
means defining an inlet duct for one of said particulate materials,
a lining in said duct, said lining being parallel to said axis of
said roll and being directed towards said gap and means for
adjusting said lining in a direction that is radial in relation to
a radial plane of the roll containing the gap.
9. The apparatus as claimed in claim 7 wherein said knives are
detachably secured in place, at least one of said units having a
shroud to take the place of one such knife and extending at least
substantially concentrically about part of an outer face of the
roll in said unit and past a lowest point of such outer face.
10. The apparatus as claimed in claim 9 comprising near a point of
attachment of said shroud means supporting said shroud so that same
may be rocked about a further axis parallel to said axis between an
active position in which said shroud is parallel to said outer face
and an inactive position and means for locking said shroud in both
of said positions.
11. The apparatus as claimed in claim 5 wherein each metering unit
comprises two such ribbed rolls in parallelism, means for driving
said rolls in opposite directions at the same speed as each other
with rib-to-rib rolling contact in the manner of meshing gears, and
means for adjusting the distance between the axis of said rolls in
each said unit and for turningly setting one roll in relation to
the other.
12. The apparatus as claimed in claim 5 wherein said ribs on said
rolls have such a helical angle about the axis of said roll that
ends of each rib are spaced apart from each other in a
circumferential direction by a distance equal to the
circumferential pitch of the ribs.
13. The apparatus as claimed in claim 5 wherein said ribs have a
rounded cross section.
14. An apparatus for mixing at least two particulate materials
together with a given mixing ratio as part of a process plant
requiring such materials in operation, said apparatus comprising: a
level, planar conveyor belt running to a processing zone within
said plant, at least two metering units placed one after the other
in succession in the direction of conveyance of said belt, each
metering unit has means defining a metering passage for flow of one
of said particulate materials therethrough, said passage stretching
from an inlet port to an outlet port, each said metering passage is
vertical for supply of material to said roll and discharge of
material therefrom, said passage having angular wall faces with
respect to the vertical, a rotary ribbed roll placed in said
metering passage for rotation about an axis running through said
passage transversely thereof, said roll having ribs thereon
bordering shallow trough-like depressions therebetween, said ribs
being helical with respect to said axis and running from end to end
of said roll, units being adapted to meter said particulate
materials at least substantially continuously, and said metering
units having outlets adapted to discharge said materials in a free
fall onto said belt with a distribution onto substantially the full
width of said belt.
15. The apparatus as claimed in claim 14 wherein said wall faces
depart from the vertical from below.
16. The apparatus as claimed in claim 11 comprising means for
changing the distance between the axes of the rolls, this said
means being adapted to move one of said rolls together with a part
of the means defining said passage tangent to said roll.
17. The apparatus as claimed in claim 5 wherein each unit comprises
a housing defining a supply zone over its roll, said housing having
a section able to be removed.
18. The apparatus as claimed in claim 5 wherein each unit comprises
a housing defining a supply zone over its roll, said housing having
a section able to be rocked out of place.
19. The apparatus as claimed in claim 5 wherein at least one of
said rolls is hollow and is fitted with duct connection means for
the supply and removal of heating fluid thereto and therefrom.
20. The apparatus as claimed in claim 4 wherein said conveyor belt
has a discharge end that is adjustable in the direction of
conveying of said belt.
21. The apparatus as claimed in claim 20 comprising a frame in
which said conveyor belt is mounted, said frame being able to be
adjusted in the direction of conveying.
22. The apparatus as claimed in claim 4 comprising a magnetic metal
removing means placed between said units and a discharge end of
said conveyor belt and running across said belt.
23. The apparatus as claimed in claim 4 wherein said conveyor belt
is fitted with magnets and with a stripper means placed downstream
from a discharge end of said belt.
Description
BACKGROUND OF THE INVENTION
The invention relates to the mixing of particulate materials and
more particularly but not exclusively to a method of mixing
particulate materials with a given mixing ratio as part of a
process requiring such materials and to an apparatus for performing
the method. As used herein the term "particulate" does not limit
the particles in the materials to any specific size or range but is
merely to distinguish the materials from fluids or solid masses in
one piece.
Difficulties are likely to be experienced in connection with the
mixing of particulate materials having different specific gravities
and/or different forms of the particles to get a given mixing ratio
more particularly in those cases in which the paramount objective
is not to produce an overall mixture containing given proportions
of the individual components but rather to make certain that the
distribution of the components in the mixture is as even as
possible so that even if some fractions are relatively small the
desired mixing ratio is in fact adhered to and/or if the mixing
operation is to take place in a more or less continuous process.
Even if it proves feasible to supply the amounts of the starting
materials in the desired mixing ratio at least substantially
continuously to a given position, there is bound to be a certain
distance between the metering units supplying the different
components of the mixture, or between the outlets of the units, so
that the starting components will be separated from each other in
space accordingly. It is not in fact possible for the components
separated in this way to be supplied at one point by using a sort
of hopper device because the components with their different
specific gravities and other different properties may well adhere
to a different extent and more specially in an uncontrolled manner
to the wall faces or baffles of such apparatus so that there will
be fluctuations in the mixing ratio. Mechanical mixing devices such
as mixing drums, agitators, or the like also prove unsuccessful
because with such differing properties of the components they are
not able to mix the components evenly; a further telling point is
that the transport from the mixing plant to the processing zone is
likely to cause a further uncontrolled change in the mixing
ratio.
In order to make the position clearer, the aim of the invention
will now be elucidated on the basis of a practical example without
this however limiting its field of application.
Synthetic resin components, now specially in the form of comminuted
resin waste, may be supplied to a heated roll crusher and
plastified there under the effect of heat and pressure so that such
resin may then be immediately made into articles or, on the other
hand, granulated. The components then supplied together may be
quite different, as for example resin fragments produced by a
cutting mill, plastic foil broken down into the form of flakes, or
resin in powder form as well, for example for improving the quality
of regenerated material.
To make certain that the plastified resin coming from the crushing
rolls may be produced with an even quality it is necessary to see
that the mixture of the different components is supplied to the
rolls with a constant mixing ratio. For optimum operation of the
rolls the component should be applied to them in the form of an
evenly distributed, coherent, thin or single-thickness layer to
make certain that the component is held fast by the foil coating of
plastified resin on the roll and is successfully moved along into
the crushing or squeezing zone. Therefore the specific problem to
be solved is to supply different components with a given mixing
ratio, that will vary from case to case, in the form of a
relatively thin layer where processing is to take place and
furthermore to see that the given mixing ratio is adhered to in the
layer as well. Expressed generally, it is therefore possible to say
that one aim of the present invention is to devise a method for
mixing particulate mixture components with a given mixing ratio as
part of a process requiring such materials such that the mixing
ratio is adhered to even in the case of small amounts of the
components till the components are fed into the means where such
further processing takes place.
Because it is not possible to avoid separation of the components of
a mixture during transport in containers and/or during temporary
storage, the object of the invention is limited to improving the
mixing operation as a part of a process including other
operations.
In order to effect these and other objects of the invention, the
components are separately metered out by means of a metering device
operating at least substantially continuously and are distributed
from the outlet of the metering device in a free fall onto a level,
planar conveyor belt and are supplied in a further free fall from
an output end of the belt into a further processing zone, the
components preferably being distributed onto the conveyor belt in
superposed layers.
By suitably matching the output rate of the metering units and the
speed of the conveyor belt it is possible to produce a
correspondingly thin layer which nevertheless keeps to the desired
mixing ratio on the conveyor belt. Since the belt is moved on the
level and in a planar form, there is no change in the position of
the layer of component before it is discharged from the belt. Since
the component passes from the discharge end of the belt to the
further processing zone, it will arrive thereat with the desired
mixing ratio as well
Because furthermore the component is distributed onto the conveyor
belt in a thin layer, it is quite a simple step to remove metallic
impurities from it on its way from the metering unit to the
discharge end of the conveyor belt, such impurities resulting from
wear of the metering units or otherwise finding their way into the
layer of material as a component in the form of waste resin as
supplied.
Therefore in keeping with a further useful development of the
invention, the component located on the conveyor belt is freed of
metal particles by a magnetic separator.
A further aim of the invention is to devise an apparatus for
performing the method.
In keeping with the invention such an apparatus comprises a
conveyor belt guided on the level and in a planar form as far as a
point over the further processing zone to be supplied with the
mixed components, a number of metering units for particulate
components placed one after the other in the direction of
conveying, such units operating at least substantially
continuously, so that the component discharged therefrom and
falling freely arrives on the conveyor belt generally over its full
width.
For undertaking the method it is desirable that the separate
components be metered out as continuously as possible. This is made
possible by a particularly convenient development of the invention
in keeping with which there is at least one ribbed roll in the
metering passage of each metering unit between a feed port and an
outlet port, such roll being able to be rotated about an axis
running through the said metering passage transversely, and being
furnished with shallow groove-like depressions placed successively
in the circumferential direction and separated from each other by
helical ribs from one axial end thereof to the other.
Because of this the separate depressions only take up a relatively
small amount of component, it being possible by having a suitably
large number of depressions to provide for a generally continuous
discharge of the material. This effect is even further enhanced
because the depressions run helically. This leads to a scattering
effect in the direction of the axis of the ribbed roll and the
discharge of component starts for example at one end of the ribbed
roll, while it terminates at the other end of the ribbed roll.
Since the mixing method of the present invention lends itself
particularly well to the mixing of components that are different in
nature, as for example components with a granular, powder-like,
lamellar or flake-like structure, it is particularly useful if the
metering units may be adapted to the material of different
components or may be adapted for this by substitution.
As an example of this, in keeping with a beneficial further
development of the invention, the metering unit comprises two
ribbed rolls arranged to be rotated about parallel axes
synchronously in opposite directions, such rolls occupying the
metering passage and having ribs adapted to mesh with each other
like helical gearing, the distance between the axes of the rolls
and the angle between the rolls as related to the circumference
being adjustable.
This makes it possible to shut off the metering passage completely
so that there is not the least chance of components leaking out,
this being accomplished by turning one of the two rolls in relation
to the other so as to make meshing engagement with the sides of the
ribs thereon, whereas for metering a granular component a space is
maintained between the ribs, corresponding to the maximum grain
size, in the engagement zone.
If at least a part of the components to be mixed consists of resin
or plastic foil comminuted into a flake-like form, there is a
danger of the foil-like components fouling the ribs and the housing
delimiting the metering passage so that the component becomes
heated by friction and causes a stoppage of the metering unit with
the result that operation may only be resumed after the metering
unit has been cleaned. It is more specially in the case of
operation of crushing rolls as noted that a given mixing ratio
should be adhered to as closely as possible and furthermore
continuous running of the apparatus is to be ensured.
To this end a further advantageous form of the invention is such
that only a single ribbed roll is placed in the metering casing and
the metering passage is limited by a knife that is fixed in
relation to the ribbed roll so that its knife edge is adjacent to
the roll, the outer edges of the ribs running towards the knife
edge being designed as cooperating cutting edges.
In the event of large pieces of foil making their way through the
comminuting means when comminuting foil-like synthetic resin, such
pieces will not be taken up in the shallow, trough-like
depressions, if they are very large, so that they will remain
within the feed opening of the metering unit and may be removed
therefrom. Smaller lumps, which are not yet in the desired flake
form, are taken up in the trough-like depressions and are moved as
far as the cutting zone at the knife where they are comminuted so
that such foil-like component is not able to jam and interfere with
continuous operation with a constant mixing ratio.
Preferably there is a guide face or lining that is parallel to the
axis of the ribbed roll so as to delimit a feed duct in the
direction of running of the ribbed roll so as to run towards the
cutting gap between the knife and the ribbed roll, such guide face
being adjustable in relation to the radial plane, containing the
cutting gap, in a radial direction so that the metering unit may be
adapted for the processing of foil component with a small cutting
gap or the processing of a more typically granular component with a
larger cutting gap.
Further advantageous and convenient forms of the invention will be
seen from the claims.
Using the following account a detailed explanation will be given of
working examples of the invention to be seen in the drawings.
LIST OF THE VARIOUS VIEWS OF THE DRAWINGS
FIG. 1 is a diagrammatic and partly sectioned elevation of an
apparatus for processing synthetic resin with a mixing device in
keeping with the invention.
FIG. 2 is a section taken on the line II--II of FIG. 1.
FIG. 3 is a diagrammatic section of a metering unit for the mixing
device.
FIG. 4 is a plan view of the metering unit as seen in FIG. 3.
FIG. 5 is a diagrammatic section taken through a clutch device
located in a ribbed roll forming part of the metering unit.
FIG. 6 is a diagrammatic section through a second working example
of a metering unit.
FIG. 7 is a diagrammatic section through a third embodiment of a
metering unit.
FIG. 8 diagrammatically shows the metering unit of FIG. 7 in plan
view.
FIG. 9 is a view corresponding to that of FIG. 7 after adaptation
of the apparatus.
FIG. 10 is a diagrammatic elevation of the end, to be seen on the
left in FIG. 1, with a metal removing device used therewith.
DETAILED ACCOUNT OF EMBODIMENTS OF THE INVENTION
A mixing apparatus generally referenced 31 will now be explained in
its function as a feed unit for conventional crushing rolls 10 for
the processing of synthetic resin and more specially of waste
synthetic resin. However it is to be noted that the mixing
apparatus may be used for other purposes.
The roll crusher 10 is made up of a housing 12, in which a roll
chamber 14 with a level axis is formed to receive a heated crush
roll 18 mounted for rotation and with a radial clearance from the
inner wall face 16 of the roll chamber 14. There is an upright feed
duct 22 running down into the annular space 20 between the roll 18
and the inner face 16. This space 20 is shown out of scale to be
larger than it would be in proportion. In the crusher there are
three crushing segments 24, 24b and 24c in the space 20, that in
each case shut off the annular space but for a narrow gap so that
the resin component heated in the roll crusher 10 is at the same
time subjected to a heavy crushing action action. Downstream from
the last crushing segment 24 the resin component plastified by heat
and pressure is forced off by a stripper 28 into an outlet duct
26.
To make certain of reliable feeding of the roll crusher and to
maintain the desired quality standard it is necessary for resin
component to be distributed over the full axis length of the
crushing roll 18 with a constant mixing ratio as a relatively thin
layer, because on the one hand there is a decrease in the driving
power needed with a decrease in the thickness in the layer of
component, and on the other hand there is the danger of a blockage
of the component in the inlet gap 38 into the annular space 20, if
the layer thickness is excessive and not all the particles of
component supplied may be entrained by the sticky film covering the
crushing roll. It will be clear without further explanation that
fluctuations in the mixing ratio will lead to a reduction in
quality.
In order to be able to supply the roll crusher with the thinnest
possible layer of resin components at a given but nevertheless
adjustable mixing ratio, the plant is equipped with the mixing
apparatus 31, the present example of the invention, for
simplification, being limited to the mixing of only two components
or starting materials so that accordingly there are only two
metering units 32 for such two components. If a greater number of
different components are to be mixed, then there will be a number
of metering units 32 corresponding to the number of components,
without however modifying the general teaching as presented in the
example shown.
The components are each placed in one such feed duct 22 forming
part of one of the metering units 32. The metering units 32 are
placed vertically over and successively in the direction of
conveyance of a level conveyor belt 34 that is run in a planar or
flat condition and whose discharge end 35 is located over the feed
duct 22 of the roll crusher 10. The breadth of the ports 36 for the
feed of components of the metering unit 32, the breadth of the
conveyor belt 34 and the breadth of the feed duct 22 are so sized
that the component coming out of the feed ports and being deposited
on the conveyor belt 34 is in the form of a thin layer and is
distributed or scattered over the full axial length of the crushing
roll 18 on same in which said component forms a film of plastified,
sticky resin coating the crushing roll 18 and being entrained
thereby.
Each of the metering units 32 produces a thin component layer on
the conveyor belt 34 whose thickness depends on the one hand, as
will be later explained, on the speed of operation of the metering
unit 32 and on the other hand on the speed of travel of the
conveyor belt 34. Dependent on the number of metering units 32
placed successively in the direction of conveying of the conveying
belt 34 a number of layers of component are placed on the belt one
on top of the other before the end of the belt is reached, the
thickness of the layers being controlled by a suitable adjustment
of the metering units and being able to be set to a preset mixing
ratio, whereas the absolute layer thickness may be adjusted by
modifying the speed of the belt 34 while keeping the mixing ratio
unchanged.
To make certain that despite a modification of the belt speed the
component moving down in the trajectory 40 at the discharge end of
the belt falls onto the further processing zone, that is to say in
the present case, the crushing roll 18, as desired, the discharge
end may be adjusted by moving it in the direction of conveying. For
this purpose the conveying belt 34 is mounted in a frame 41 that
may be changed in position along a guide 38. There is a driving
screw 44 mounted in a base 42 carrying the guide 38, the screw 44
having a handwheel 46 and running through a lead nut 48 fixed on
the frame 41 so that if the handwheel 46 is turned the position of
the frame 41 and therefore of the discharge end 35 of the conveyor
belt 34 may be adjusted.
In order to keep up an even distribution of the component coming
out of the metering units 32 on the conveying belt 34 as far as the
end of the conveying belt 34, the conveying belt 34 is placed on
the level and furthermore its top run 50, that undertakes the
conveying function as such, is carried on a support plate 52, that
furthermore keeps the upper run 50 flat in a direction normal to
the direction of motion so that there will be no danger of the
component layer becoming thicker towards the middle of the belt or
at its edges as might be the case if the belt were to take on a
camber in the transverse direction. Since the belt is to be covered
with component generally right over the full width thereof, lateral
baffles 54a and 54b are present, that bridge the gap between the
lower end of the metering units 32 and the conveyor belt 34 and
overlap lateral ribs 56a and 56b placed near the side edges of the
conveyor belt 34, and keep component coming from the metering units
32 from falling off the side of the belt 34.
It is not possible to use conventional metering units to meter out
different sorts of component, as for example those of a granular or
powdery nature, or flake-like components as produced by comminuting
waste foil, as may be required, and to ensure the flow of the
component in an at least approximately continuous current as is
more specially important for performing the method of the
invention, to the conveyor belt 34, such current not being
excessively dense. With reference to FIGS. 3 to 5 a metering unit
will be described, that is on the one hand suitable for the mixing
method as explained and for metering out granular or powder-like
components.
Between the feed duct 30 and the discharge port 36 a generally
rectangular housing 86 delimits a metering passage containing two
parallel ribbed rolls 58a and 58b that are driven at the same speed
in oposite directions. The roll 58a to be seen on the left has a
fixed axis of rotation in the housing 86 while the roll 58b on the
right is mounted in bearings 59 able to be shifted in level guides
61 in the housing 86. Such adjustment is undertaken by way of
driving screws 63 that are turningly joined to the bearings 59 but
may not be moved in an axial direction, such screws fitting into
lead nuts 65 mounted on the housing 86 while the free ends of the
screws are for example made square at 67 so that a crank key may be
used therewith.
The ribbed rolls 58a and 58b are furnished with a number of
relatively shallow, rounded depressions 60 separated by ribs 62
that together with the depressions are helically placed in relation
to the axis of the roll 58a or 58b. The ribs 62 of the two rolls
58a and 58b are arranged to mesh with each other like the teeth of
helical gearing. The flanks of the ribs 62 are so formed that,
provided the spacing and relative angle of the two rolls 58a and
58b is correct, the ribs engage like the teeth of gears with
rib-to-rib, rolling contact.
To make such an adjustment of the two ribbed rolls 58a and 58b it
is not only necessary to shift the ribbed roll 58b in a horizontal
direction using the screws 63 but furthermore to shift the roll 58b
in the circumferential direction in relation to its shaft. As will
be seen from the diagrammatic view of FIG. 5 in accordance with one
possible form of the invention the ribbed roll 58b is joined with
its shaft 71 by a conical clutch 69. The shaft 71 is hollow and
contains a screw-threaded setting rod 73 that has a square
outwardly protruding end 75 on which a crank may be fitted. At the
clutch the shaft 71 has a slot with a dog 79 running therethrough
to the outside. Inside the shaft 71 the dog 79 has a threaded hole
receiving the setting rod 73. The dog 79 cooperates with a gripping
cone 81 which is able to be shifted in an axial direction and as
part of the conical clutch cooperates with a cone 83 joined to the
ribbed roll 58b.
If the threaded rod 73 is turned so that the dog 79 (which may not
be turned in relation to the shaft) is moved to the right in terms
of FIG. 5, the conical clutch will be disconnected, possibly with
the aid of a spring that is not shown, so that the ribbed roll 58b
may be turned in relation to the shaft 71. Afterwards the setting
screw 73 is turned back in the opposite direction and the dog 79
will clamp the two parts 81 and 83 of the conical clutch firmly
together so the ribbed roll 58b is keyed on the shaft 71 again.
If desired it is possible to have a clutch at both ends of the
ribbed roll 58b, in which case the setting rod 73 will have to
extend along a greater length of the shaft 71.
In a drive box 101 located on one end face of the housing 86 there
is a chain for driving the two ribbed rolls 58a and 58b at the same
speed in opposite directions. Each of the two ribbed rolls 58a and
58b has its own sprocket wheel 103 and 104 and the drive chain 102
crosses the plane containing the axes of the two ribbed rolls 58a
and 58b so that the sprocket wheels 103 and 104 are driven in
opposite directions. The driving chain 102 is trained over two
idler wheels 105 and 106, of which the one 105 is able to be
adjusted, as is diagrammatically indicated by the guide 107 and a
screw setting rod 109 (see FIG. 4) having a square end 108. It will
therefore be seen that changes may be made in the spacing between
the axes of the ribbed rolls 58a and 58b for compensatory
adjustment, whereas on the other hand it is possible for the
direction of turning of the ribbed rolls 58a and 58b to be reversed
as for example for cleaning.
To improve access to the ribbed rolls 58a and 58b for the removal
of any component fouling them and generally to facilitate cleaning,
the upper housing part 86' may be folded upwards about a hinge
91.
The drive of the ribbed rolls 58a and 58b is for example by way of
the stub shaft 94.
In a state of adjustment that is suitable for metering out granules
or small resin particles, as for example from a cutting mill, the
relative angle between the two rolls is so chosen the in the
meshing zone of the two rolls the rib 62 of the one roll projects
exactly into the middle of the depression 60 opposite to it in the
other roll, the flanks of the ribs 62 not being in contact and in
fact there is a gap corresponding to the maximum allowable size of
particle between them. In this respect the distance between the
axes of the two rolls 58a and 58b is so set that the limit of the
rib running in the circumferential direction of the one roll keeps
to a corresponding distance from the floor of the depression 60 in
the other roll.
If particles exceeding the maximum size find their way into the
zone of engagement of the ribs they will be crushed down to such
size by the force of the rolls 58a and 58b.
By making a suitable change in the angular setting and the spacing
between the axes the apparatus may be set for different sizes of
particles if desired.
In order to meter out powder components as well, the two ribbed
rolls are best so set that the flanks of the ribs 62 engage each
other gearingly with rolling contact to keep such powder from
freely flowing through gaps between the ribs without full
control.
By moving the rolls 58a and 58b closer together for metering powder
components a gap would normally be formed between the part of the
roll 58b and the inner face 86 of the housing, through which the
component would then be able to flow, even although such flow would
be limited by the upward motion of the face of the ribbed roll 58b
at this position. It is therefore best if the housing is fitted
with an inner wall lining 72' here joined to the bearings 59 and
able to be adjusted together with them and the ribbed roll 58b. The
lining is then placed closely adjacent to the periphery of the
ribbed roll 58b.
For metering flake component as for example that produced by
comminuting plastic or synthetic resin foil or for material resin
that may contain foil-like fractions, the forms of the metering
unit to be seen in FIGS. 6 to 10 are more specially suitable. These
metering units each have only one single ribbed roll 58 of the sort
noted hereinbefore, that is furnished with relatively shallow
depressions 60 which in cross section will be seen to be rounded in
order to reduce adhesion of component.
The ribs 62 between the depressions 60 cooperate with a knife 66,
that is mounted on the inner wall face of the chamber containing
the ribbed roll, the cooperation being such that the leading edges
68 of the ribs 62 cut the component against the cutting edge 70,
running parallel to the axis of the ribbed roll 58. In order to
produce an efficient drawing cut, the depressions 60 and the ribs
62 are oblique in this case as well in relation to the axis of the
ribbed roll 58 and preferably in such a way that at one axial end
of the ribbed roll 58 the leading edge of one rib 62 ceases to make
shearing contact with the cutting knife 70 just when at the other
end of the roll 58 the leading edge 68' of the following rib 62'
starts to make shearing engagement with the cutting knife 70.
The inner wall lining 72 forming the limit of the feed duct 30 in
the direction of motion of the ribbed roll 58 is straight as far as
a point adjacent to the knife 70 so that a wedge-like or tapering
intake gap 74 forms, through which the component is supplied to the
cutting zone and the metering rib depressions. In the event of the
component jamming in the cutting zone the direction of rotation of
the ribbed roll 58 is reversed. Since the arrangement is
symmetrical, that is to say there is a knife 66 or 66' for each
direction of turning, such a reversal is possible at any time. In
order to make certain that the metering unit will operate
continuously it is furthermore possible for there to be means
monitoring the torque at the ribbed roll shaft and automatically
reversing the direction of rotation as soon as the torque exceeds a
given threshold.
This arrangement is well adapted to the supply of foil-like
components inasfar as such foils are drawn into the feed duct 74
and because of the closeness together of the ribs 60 and
furthermore because of the small volume of the depressions 60 such
components will leave the metering unit 32a in all cases in the
form of a relatively thin descending curtain of flake-like
particles, even if the material supplied to the feed duct 30 is in
the form of coarse pieces of foil.
In order to make it possible to use a metering unit of this type
for other foil-like or other fine-grained components, the metering
unit 32b in the design of FIGS. 7 and 8 is such that access to the
cutting zone is adjustable, because in addition to the structure to
be seen in FIG. 6 the inner lining 72' leading to the draw in gap
74' is able to be adjusted radially in the diametral plane running
through the knife cutting edges 70', the range of such adjustment
being indicated more or less diagrammatically by four screws 78
joined with each inner lining 72', such screws being guided
parallel to each other by respective fixed outer wall elements 80
forming the housing of the unit. Such screws are furthermore taken
through pairs of outer straps 84, that are spaced from the wall
elements 80 and are joined to the housing generally referenced 86
of the metering unit 32b. The screws run through sleeves fixed to
the elements 80 for parallel guidance and they run through holes in
the upright pairs of straps 84. Such straps are spaced from the
wall elements 80 and are joined to the housing, generally
referenced 86 of the metering unit 32. Nuts on the screws 78 are
placed on each side of each strap 84, such nuts making it possible
to adjust the screws and for this reason the wall linings 72'
therein in a direction parallel to the diametral plane running
through the knives 70' and to lock such linings in position after
such adjustment. The distance of the inner faces of the linings 72'
from the knives 70' will be so set taking into account the maximum
particle size that only parts are able to make their way into the
cutting zone which may be comminuted down to the maximum particle
size.
In the case of the two last-described forms 32a and 32b of the
metering unit the knives 66 and 66' respectively are made with
slots 90 and may be adjusted using fixing screws 92.
If on the one hand foil-like material and on the other hand
relatively hard granular material is to be metered the form of the
invention of FIG. 9 may be employed with advantage. In fact there
is a danger of excessively hard material causing an unacceptably
high rate of wear of the knives 66 and 66' designed for the
comminution of foils. If on the other hand one were to remove the
knife 66 or 66' placed in the direction of turning of the ribbed
roll 58 (viz. the left hand knife in the case of counterclockwise
rotation), the granular material would be able to run
uncontrolledly through the gap then left open. Therefore in FIG. 9
the knife 66 has been removed and replaced by a guide shroud 47
that is secured in place so as to be concentric in relation to the
periphery of the roll. The lining 72' fixing the size of inlet into
the gap between the ribbed roll 58 and the guide shroud 47 is
correspondingly set back towards the outer wall element 80 in order
to widen the inlet gap. The guide shroud 47 is continued past the
lowest point of the ribbed roll 58 to keep the particles working
their way inbetween the ribbed roll 58 and the guide shroud 47 from
immediately falling out downwards under the effect of gravity,
something that would impair the metering efficiency. In fact, the
particles are lifted up by the ribbed roll as far as the end (on
the right) of the guide shroud 47, from which position they then
fall through the discharge port of the metering unit 32c.
By reversing the direction of turning of the ribbed roll 58 it
becomes possible to use this metering unit 32c with the described
adaption for metering foil-like or granular component as may be
desired.
To ensure that when operating with the knife 66' the foil flakes do
not pass onto the guide shroud 47 of the metering unit 32c, because
they might then possibly be entrained by the ribbed roll 58
somewhat past the cutting edge 70', the guide shroud 47 may be
rocked about a shaft 49 running parallel to the axis of the ribbed
roll 58 in the cutting zone so that the shroud 47 is able to be
moved out of the position under the ribbed roll 58 into a resting
position, that is marked in FIG. 9 with a broken line. It may be
locked in this position by a bolt fitting into a hole 45 for
example. The same type of locking system may be utilized for the
working position as well.
For processing waste resin attempts have admittedly been made in
the past to remove pieces of metal, for example by using metal
detectors and/or magnetically operating metal removing means, more
specially for removing steel parts or particles which might
otherwise make expensive repairs to plant necessary. However in
practice experience has show that it is nevertheless possible of
pieces of metal to make their way into comminuting machines as for
example cutting mills, such pieces of metal occurring with
particles resulting from wear, as for example fractured parts of
cutting members, may be found in the particulate material that is
to be fed into roller presses. In order to avoid expensive repairs
and to improve the quality of the resin products made, these
particles are to be removed from the material to be processed
before it reaches the roller press, the formation of a thin layer
of material on the conveyor belt offering a particularly good
opportunity for doing this, because the distance between a magnet
and any metal particles to be removed may be made very small and
the resistance of the non-metallic pieces of material to removal of
the pieces of metal is very small because of the thinness of the
layer.
Therefore for example, see FIG. 10, a diagrammatically shown device
23 for magnetically removing metals is placed across the full width
of the conveyor belt 34 between the metering units 32 and the
discharge end 35 of the conveyor belt 34. The distance between the
device 23 and the conveyor belt 34 may preferably be adjusted in a
vertical direction. The device may for example be a magnetic bar
with a cleaning device or a belt crossing the conveyor belt 34,
that is either itself magnetic or runs on the side, facing the
conveyor belt 34, of a magnet and has a stripper placed clear of
the conveyor belt. For example, the cleaning belt may be fitted
with permanent magnets.
The magnetic bar may be in the form of a beam fitted with
electro-magnets and which is able to be turned about an axis
running transversely in relation to the direction of motion of the
conveyor belt 34 so that alternately one of at least two faces,
that are at different angles, may be moved into an operating
position in relation to the conveyor belt 34, the other face or
faces then being cleaned.
In accordance with a further possible form of the invention, the
bend roll 36 at the discharge end 35 of the conveyor belt 34 is
fitted with magnets so that it has the effect of a metal removing
device retaining pieces of metal on the conveyor belt while the
non-magnetic ones are discharged therefrom. To make for a better
separation between the non-magnetic resin particles and the
separated pieces or particles of metal, it is possible to have a
further plate 39 fitted with magnets next to the bend roll 37 under
the lower run 51 of the conveyor belt 34. Using a stripper 45' and
a guide board 43 it is then possible to clear separated metallic
objects out of the way.
As a further form of the invention it is possible for the conveyor
belt 34 itself to have embedded permanent magnets in it, in which
case however the pieces of metal will be also moved around the bend
roll 37 and will be detached by the stripper 45' from the conveyor
belt 34, whereas the resin particles will be thrown off at the
discharge end 35.
For efficient removal of metal the belt speed should be such that
the layer is as thin as possible and in the case of material with a
granular structure the grains do not rest on top of each other so
that they do not oppose the magnetic removal of material.
The ribbed rolls 58, 58a and 58b are made hollow so that it is
possible in a conventional way (which does not need any detailed
explanation here) for connections to be made for the supply and
removal of heating fluid through the stub shafts running out from
the two sides of the housing 86, as for example at 94 and 96 in
FIG. 8. In many cases, as for example in connection with processing
resin in a roller press heated coolant is available which may be
used to preheat the material to be metered out.1 In connection with
the plastification of resin this may on balance lead to a reduction
in the total amount of energy needed.
* * * * *